UNIVERSITY  OF  CALIFORNIA  AGRICULTURAL  EXPERIMENT  STATION 

COLLEGE  OF  AGRICULTURE  Benj.  ,de  Wheeler,  President 

BERKELEY,  CALIFORNIA  Thomas  Forsyth  Hunt,  Dean  and  Director 


CIRCULAR  No.  90. 


TUBERCULOSIS  IN  CATTLE  AND  HOGS. 

By  C.  M.  Haring. 

Bovine  tuberculosis  is  a  menace  that  no  stock  raiser  or  dairyman  can 
afford  to  ignore.  Over  twenty  per  cent  of  one  thousand  cows,  recently 
tested  in  seven  different  counties  in  the  San  Joaquin  Valley,  reacted  to 
the  test,  and  were  condemned.  Furthermore,  the  disease  is  increasing. 
Figures  from  the  reports  of  meat  inspectors  in  San  Francisco  show  that 
the  number  of  cattle  coming  from  this  valley,  which  are  affected  with 
tuberculosis,  has  increased  from  nine  tenths  of  1  per  cent  to  9  per  cent 
in  five  years.  The  economic  losses  from  the  disease  are  enormous, 
amounting  to  over  half  a  million  dollars  per  year  in  this  State  alone. 

The  loss  of  human  life  due  to  tuberculosis  contracted  from  infected 
animals  is  of  infinitely  greater  consequence  than  the  tremendous  eco- 
nomic loss.  Scientific  investigations  indicate  that  a  certain  percentage 
of  human  tuberculosis  is  of  bovine  origin,  the  germs  being  readily  trans- 
ferable through  the  milk,  butter,  and  improperly  cooked  flesh  of  infected 
animals. 

The  disease  is  readily  transmitted  from  cattle  to  children  when  in- 
fected cows'  milk  is  largely  used  as  food.  It  is  admitted  by  the  best 
authorities  that  intestinal  tuberculosis,  skin-tuberculosis,  and  bone- 
tuberculosis  of  man,  are  often  of  bovine  origin ;  researches  by  Dr.  Park 
of  the  New  York  City  Board  of  Health  indicate  that  about  12  per  cent 
of  the  total  infections  from  tuberculosis  in  children  are  due  to  infection 
from  bovine  sources.  . 

Symptoms  of  Tuberculosis  in  Cattle. 

There  is  no  symptom  that  can  be  relied  upon  as  a  certain  indication  of 
the  disease,  since  each  may  in  some  cases  be  caused  by  other  diseases  or 
conditions.  Following  are  the  more  frequent  symptoms  which  may 
possibly  indicate  tuberculosis  in  cattle: 

Loss  of  Flesh  and  Unthriftiness. — The  coat  becomes  rough,  the  skin 
feels  harsh  and  thick  and  there  is  a  gradual  loss  of  flesh  without  a  loss 
of  appetite. 

Cough. — This  symptom  is  only  present  when  the  disease  is  attacking 
the  lungs  or  some  part  of  the  breathing  organs.  It  is  not  a  loud  cough, 
but  rather  a  subdued  and  infrequent  one,  and  may  at  first  be  heard  only 
when  the  animal  is  driven.  At  a  later  stage  of  the  disease  it  may  be 
heard  at  any  time  of  the  day.  Cows  do  not  usually  appear  to  cough  up 
anything.  This  is  because  they  do  not  spit.  Most  of  the  material 
coughed  up  from  the  lungs  is  swallowed,  but  many  tuberculosis  germs 

(l) 


—  2  — 

escape  from  the  mouth  in  the  form  of  spray,  or  are  discharged  from 
the  nose.  Symptoms  of  lung  infection  other  than  cough  are  wheezing 
or  snoring  respiration  and  labored  breathing  on  being  exercised. 

Enlarged  Glands. — Enlargements  in  the  region  of  the  throat,  espe- 
cially when  they  cause  difficulty  in  breathing,  are  very  apt  to  be  due  to 
tuberculosis. 

Loss  of  Appetite.— This  symptom  is  not  seen  until  the  later  stages  of 
the  disease,  when  the  animal  is  evidently  wasting. 

Bloating. — Sometimes  the  diseased  glands  in  the  chest  prevent  the 
usual  passage  of  gas  from  the  paunch  to  the  mouth  by  pressing  on  the 
gullet.  In  this  case  the  cow  suffers  from  bloating,  and  the  paunch  is 
often  greatly  distended  with  gas.  This,  however,  is  not  a  very  frequent 
symptom. 

Diarrhea. — Looseness  of  the  bowels  or  "scouring"  is  seen  in  cattle 
affected  with  the  disease  in  the  bowels.  This  kind  of  scouring  cannot  be 
cured  by  any  known  treatment. 

Hard  Lumps  in  the  Udder. — When  tuberculosis  attacks  the  udder  no 
•change  can  be  detected  at  first,  but  after  a  time  hard  lumps  can  be  felt 
in  some  parts  of  the  organ  after  it  is  milked  out.  Milk  from  such  an 
udder  must  not  be  used,  as  it  is  almost  certain  to  be  teeming  with  germs 
of  the  disease. 

Post-mortem  Appearances. 

When  the  carcass  of  the  cow  affected  with  tuberculosis  is  opened  the 
disease  may  be  found  in  any  part  of  the  body,  but  it  is  usually  located 
in  the  lymph  glands  of  the  chest,  throat,  or  abdomen.  Tissues  showing 
lesions  of  tuberculosis  in  cattle  and  hogs  can  be  seen  in  the  veterinary 
exhibit  of  the  College  of  Agriculture  at  Berkeley  and  Davis.  When  the 
disease  is  located  in  the  lungs  and  discharges  into  the  air  tubes,  pieces  of 
diseased  tissue  and  millions  of  germs  are  liberated  and  coughed  up. 
Most  of  these  are  swallowed  and  passed  out  in  the  manure.  This  is  the 
chief  way  in  which  the  germs  are  discharged  from  diseased  cattle. 

Suppression  of  the  Disease. 

The  first  step  in  getting  rid  of  the  disease  is  to  find  out  how  many  of 
the  herd  are  affected  by  it.  This  is  done  by  applying  the  tuberculin 
test.  This  will  show  a  larger  or  smaller  number  of  the  herd  to  be  af- 
fected, and  the  proper  course  to  pursue  will  depend  largely  upon  the 
proportion  of  the  reactors  found. 

Suppose  that  only  a  few  cattle  react,  say  15  out  of  100,  or  in  that  pro- 
portion. In  this  case  the  reactors  are  first  carefully  examined,  and  if 
any  of  them  show  symptoms  of  the  disease  by  coughing,  loss  of  condition, 
or  any  other  of  the  signs  by  which  the  disease  is  recognized  without  the 
test,  such  animals  should  be  slaughtered. 

The  other  reactors  should  then  be  entirely  separated  from  the  healthy 
cattle,  and  fed,  watered,  and  kept  separate  from  the  other  animals  at  all 
times.    Whenever  a  calf  is  born  among  the  reactors,  it  should  be  imme- 


—  3  — 

•diately  separated  from  its  mother  and  brought  up  by  hand,  or  on  a 
healthy  cow.  The  calf  is  usually  born  healthy,  but  would  soon  catch  the 
disease  from  its  mother  if  allowed  to  remain  with  her. 

The  milk  of  reacting  cows  may  be  used  if  it  is  first  boiled  or  heated  to 
a  point  sufficient  to  kill  the  germs.  This  heating  to  a  point  less  than 
foiling  is  called  pasteurizing,  and  is  safe,  provided  all  the  milk  reaches 
the  required  degree  of  heat  and  is  kept  there  sufficiently  long.  Heat  the 
milk  to  at  least  160  degrees  F.  and  allow  it  to  cool  gradually.  Then  feed 
to  the  calves  without  being  mixed  with  other  milk. 

This  system  of  dealing  with  tuberculosis  in  a  herd  was  planned  by 
Professor  Bang  of  Denmark  and  has  been  very  successfully  followed  in 
that  country  for  some  years.  It  has  the  advantage  of  allowing  the 
reactors  to  be  made  use  of  while  a  sound  herd  is  being  built  up.  Under 
this  system  the  sound  herd  increases  in  numbers  as  healthy  calves  are 
added  to  it,  while  the  diseased  herd  becomes  smaller  as  the  reactors  die 
off  or  are  killed  as  open  cases  of  tuberculosis. 

Dealing  With  a  Badly  Infected  Herd. 

Where  the  test  shows  more  than  half  the  number  diseased,  a  somewhat 
different  plan  is  required  than  the  Bang  system.  This  herd  is  so  badly 
affected  that  the  non-reactors  cannot  safely  be  considered  healthy.  Many 
of  them  are  sure  to  have  been  infected  with  the  disease  quite  recently, 
so  that  the  test  fails  to  detect  it.  These  will  react  at  the  next  test,  and 
in  the  mean  time  may  develop  the  disease  so  rapidly  as  to  infect  the 
others. 

For  these  reasons  it  is  better  to  treat  such  a  herd  as  if  it  were  entirely 
diseased,  and  to  begin  with  the  newborn  calves  to  building  up  a  healthy 
herd.  The  method  from  this  point  is  exactly  the  same  as  the  Bang 
system,  except  that,  as  there  are  no  healthy  cows  to  act  as  foster  mothers, 
the  calves  must  be  raised  on  pasteurized  milk.  At  6  months  old  the 
calves  are  tested,  and  reactors  are  transferred  to  the  other  herd.  This 
plan  was  devised  by  a  German  veterinary  surgeon  named  Ostertag,  and 
is  known  as  the  Ostertag  system.  It  is  very  successful  when  carefully 
carried  out. 

While  getting  rid  of  the  disease  by  whatever  system  may  be  adopted, 
an  animal  should  never  be  bought  for  the  healthy  herd  unless  known  to 
be  healthy.  The  tuberculin  test  should  be  applied,  and  if  possible  the 
animals  should  be  selected  from  a  herd  that  is  known  to  be  free  from 
tuberculosis. 

Sanitation. 

In  at  least  one  respect  the  problem  of  dairy  sanitation  is  not  as  great 
in  California  as  in  many  Gther  parts  of  the  United  States.  The  proper 
ventilation  of  stables  is  not  a  great  problem  here.  The  climatic  condi- 
tions are  such  that  tight  barns  are  unnecessary,  and  the  cows  can  live 
in  the  out-of-doors  for  a  greater  length  of  time  than  in  the  eastern  states. 
Although  this  out-of-door  life  may  be  of  value  in  lessening  the  amount 
■of  tuberculosis,  it  will  not  absolutely  prevent  its  spread.    In  dairy  cows 


—  4  — 

kept  under  outdoor  conditions,  tuberculosis  is  common.     Even  in  the 
range  cattle  of  this  State  the  disease  seems  to  be  increasing. 

Cleanliness. 

Since  the  manure  of  tuberculosis  cattle  often  contains  living  tubercle 
germs  in  vast  numbers,  the  importance  of  keeping  it  well  cleaned  from 
the  stable  and  yards  is  readily  seen.  Such  manure  is  not  only  dangerous 
to  other  cattle  in  the  stable,  but  may  be  the  means  of  conveying  the 
disease  to  children.  Often  cows  are  seen  with  their  flanks  incrusted  with 
dry  dung.  Parts  often  break  off  while  the  cow  is  milked,  and  some  of  it 
is  likely  to  fall  into  the  milk  pail.  The  larger  lumps  are  strained  out, 
but  the  smaller  particles  remain,  and  also  the  tubercular  germs,  which 
are  small  enough  to  pass  through  the  strainer.  These  stay  in  the  milk 
and  make  it  a  fruitful  cause  of  the  disease  in  young  children. 

Stables  should  be  cleaned  out  often  and  the  manure  put  where  it  can 
not  be  picked  over  by  hogs  or  cattle.  Hogs  are  easily  infected  in  that 
way.  Cleanliness  also  includes  keeping  the  walls  and  ceilings  free  from 
dirt,  dust  and  cobwebs.  These  are  all  good  resting  places  for  disease 
germs. 

The  Dairyman's  Responsibility. 

The  eradication  of  tuberculosis  is  the  task  of  the  dairyman  with  the 
assistance  of  the  State.  The  responsibility  for  the  existence  of  tuber- 
culosis and  its  continuance  rests  with  the  owners  of  the  infected  cattle. 
Remarkable  progress  has  been  made  in  eradicating  tuberculosis  without 
great  loss  in  several  dairy  sections  of  this  State.  The  men  above  all 
others  who  should  regularly  test  their  cows  are  the  ones  whose  herds 
are  free  from  the  disease.  Constant  vigilance  is  necessary  to  keep  a 
herd  of  dairy  cows  free  from  tuberculosis. 


